HEAT PUMP APPARATUS

Description

TECHNICAL FIELD

The present disclosure relates to a heat pump apparatus.

BACKGROUND ART

As existing heat pump apparatuses, various types of heat pump apparatuses that use refrigerant and a heat medium such as water have been developed. For example, Patent Literature 1 discloses a cold/hot water multi-split type air-conditioning apparatus that includes two cold and hot water generators and a plurality of indoor units installed at each of floors in a building. In this cold/hot water multi-split type air-conditioning apparatus, each of outdoor units is connected to a plurality of indoor units by cold/hot water pipes, and one of the outdoor units is used for a cooling operation and the other is used for a heating operation, whereby the indoor units can perform the cooling operation and the heating operation at the same time.

CITATION LIST

Patent Literature

• • Patent Literature 1: Japanese Unexamined Patent Application Publication No. 4-214134

SUMMARY OF INVENTION

Technical Problem

However, the cool/hot water multi-split type air-conditioning apparatus disclosed in Patent Literature 1 needs two cool/hot water pipes that are connected to one of the outdoor units to allow cold water to flow back and forth, and two cool/hot water pipes that are connected to the other of the outdoor units to allow hot water to flow back and forth. It is therefore necessary to install two cool/hot water pipes at each of outdoor units installed outdoors. Therefore, a larger number of cool/hot water pipes are installed, and the burden of piping work is thus great.

The present disclosure is applied to solve the above problem, and relates to a heat pump apparatus that needs a smaller number of pipes that are connected to a heat source unit.

SOLUTION TO PROBLEM

A heat pump apparatus according to one embodiment of the present disclosure includes a heat source unit, a relay unit connected to the heat source unit, and a plurality of load units connected to the relay unit. The heat source unit includes a first refrigerant circuit in which refrigerant is circulated and a first water heat exchanger configured to exchange heat with the first refrigerant circuit. The relay unit includes a second refrigerant circuit in which the refrigerant is circulated and a second water heat exchanger configured to exchange heat with the second refrigerant circuit. The first water heat exchanger, the second water heat exchanger, and the load units are connected by first heat-medium pipes, whereby a first heat-medium circuit is formed in which a heat medium is circulated.

Advantageous Effects of Invention

According to the present disclosure, when a plurality of load units perform cooling and heating at the same time, a first refrigerant circuit provided in a heat source unit and a second refrigerant circuit provided at a relay unit can perform cooling and heating, respectively, whereby the number of pipes that are connected to the heat source unit can be reduced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a configuration diagram schematically illustrating a heat pump apparatus according to Embodiment 1.

FIG. 2 is a refrigerant circuit diagram of the heat pump apparatus according to Embodiment 1.

FIG. 3 is a refrigerant circuit diagram illustrating a configuration of the heat pump apparatus according to Embodiment 1, in which a first pump is provided in a relay unit.

FIG. 4 is a refrigerant circuit diagram illustrating a configuration of the heat pump apparatus according to Embodiment 1, in which a heat source unit and the relay unit 2 include respective first pumps.

FIG. 5 is a refrigerant circuit diagram of the heat pump apparatus according to Embodiment 1, which indicates flows of refrigerant and a heat medium in the case where both load units perform cooling.

FIG. 6 is a refrigerant circuit diagram of the heat pump apparatus according to Embodiment 1, which indicates flows of the refrigerant and a heat medium in the case where the load units perform heating.

FIG. 7 is a refrigerant circuit diagram of the heat pump apparatus according to Embodiment 1, which indicates flows of the refrigerant and the heat medium in the cooling main operation.

FIG. 8 is a refrigerant circuit diagram of the heat pump apparatus according to Embodiment 1, which indicates flows of the refrigerant and the heat medium in the heating main operation.

FIG. 9 is a refrigerant circuit diagram illustrating Modification 1 of the heat pump apparatus according to Embodiment 1.

FIG. 10 is a configuration diagram schematically illustrating Modification 2 of the heat pump apparatus according to Embodiment 1.

FIG. 11 is a refrigerant circuit diagram of a heat pump apparatus according to Embodiment 2.

FIG. 12 is a graph indicating a relationship indicating a relationship between a cooling ratio of the load units and a ratio of a flow rate V1 of a heat medium that flows in a bypass flow passage to the total flow rate V of heat mediums that flow in the first heat-medium circuit in the heat pump apparatus according to Embodiment 2.

FIG. 13 is a refrigerant circuit diagram of a heat pump apparatus according to Embodiment 3.

FIG. 14 is a refrigerant circuit diagram of the heat pump apparatus according to Embodiment 3 in the case where heated water is generated in the first heat-medium circuit.

FIG. 15 is a refrigerant circuit diagram of a heat pump apparatus according to Embodiment 3 in the case where cooled water is generated by the first heat-medium circuit.

DESCRIPTION OF EMBODIMENTS

The embodiments of the present disclosure will be described with reference to the drawings. It should be noted that in each of figures in the drawings, components that are the same as or equivalent to those in a previous figure or previous figures are denoted by the same reference signs, and their descriptions will thus be omitted or simplified as appropriate. With respect to the components illustrated in each of the figures, their shapes, sizes, positions, etc., can be modified as appropriate.

Embodiment 1

FIG. 1 is a configuration diagram schematically illustrating a heat pump apparatus 100 according to Embodiment 1. FIG. 2 is a refrigerant circuit diagram of the heat pump apparatus 100 according to Embodiment 1. It should be noted that outlined arrows in FIG. 2 each indicate the flow of a heat medium. The heat pump apparatus 100 according to Embodiment 1, as illustrated in FIGS. 1 and 2, includes a heat source unit 1, a relay unit 2 connected to the heat source unit 1, and a load unit 3A and a load unit 3B that are connected to the relay unit 2. The heat source unit 1 is, for example, an outdoor unit. The load units 3A and 3B are, for example, indoor units. The heat source unit 1 is installed, for example, at a rooftop of the building 200. The relay unit 2 and the load units 3A and 3B are installed, for example, in the building 200.

Components included in the heat source unit 1, the relay unit 2, and the load units 3A and 3B are controlled by a controller 6.

As illustrated in FIG. 2, the heat source unit 1 includes a first refrigerant circuit 10 and a first water heat exchanger 11. In the first refrigerant circuit 10, the refrigerant is circulated, and the first water heat exchanger 11 exchanges heat with the first refrigerant circuit 10. The relay unit 2 includes a second refrigerant circuit 20, a second water heat exchanger 21, and a third water heat exchanger 22. In the second refrigerant circuit 20, the refrigerant is circulated; the second water heat exchanger 21 exchanges heat with the second refrigerant circuit 20; and the third water heat exchanger 22 exchanges heat with the second refrigerant circuit 20. The load unit 3A and the load unit 3B include respective load-side heat exchangers 30.

In the first refrigerant circuit 10, flammable refrigerant such as R290, NH₃, or olefin (R1234yf, R1234ze(E), R1123, R1132(E), etc.) is enclosed. This is because the heat source unit 1 is installed outdoors and refrigerant that has flammability, but has a small global warming effect is used. In the second refrigerant circuit 20, non-flammable or slightly flammable refrigerant such as R410A, R32, olefin, or a mixture of R410A, R32, and olefin is enclosed. This is because the relay unit 2 is installed mainly indoors. It should be noted that the refrigerant enclosed in the first refrigerant circuit 10 and that in the second refrigerant circuit 20 are not limited to the above kinds of refrigerant, and refrigerant that is currently widely used in air-conditioners, such as R410A or R32, or R290, or another kind of refrigerant that is CO₂NH₃, olefin, or a mixture refrigerant thereof may also be used. For example, flammable refrigerant such as R290, NH₃, or olefin may be enclosed in the refrigerant circuit 20 in terms of safety.

The weight of refrigerant that is enclosed and circulated in the first refrigerant circuit 10 is larger than that of refrigerant that is enclosed and circulated in the second refrigerant circuit 20. The weight of refrigerant that is enclosed in the first refrigerant circuit 10 is, for example, 5 kg or less. The weight of refrigerant that is enclosed in the second refrigerant circuit 20 is, for example, less than 1 kg that is the standard weight of flammable refrigerant in the case where the flammable refrigerant is used indoors. The first refrigerant circuit 10 is used mainly by the load units 3A and 3B whose operating loads are large. That is, in order to improve the operating efficiency, the weight of refrigerant that is enclosed and circulated in the first refrigerant circuit 10 is set greater than that of refrigerant that is enclosed and circulated in the second refrigerant circuit 20.

In the heat pump apparatus 100, the first water heat exchanger 11, the second water heat exchanger 21, and the load-side heat exchangers 30 are connected by first heat-medium pipes 40, whereby a first heat-medium circuit 4 is formed. In the first heat-medium pipes 40, a heat medium is circulated. Furthermore, in the heat pump apparatus 100, the third water heat exchanger 22 and the load-side heat exchangers 30 are connected by second heat-medium pipes 50, whereby a second heat-medium circuit 5 is formed. In the second heat-medium circuit 5, a heat medium is circulated. The first heat-medium circuit 4 and the second heat-medium circuit 5 include first flow switching devices 4a and 5a that switch flow passages for the heat medium that flows into the load units 3A and 3B such that the flow passages connect with the first heat-medium circuit 4 or the second heat-medium circuit 5. It should be noted that the heat medium is, for example, water, brine, or a mixture of water and brine.

First of all, a configuration of the heat source unit 1 will be described. The heat source unit 1 includes the first refrigerant circuit 10 in which refrigerant is circulated. In the first refrigerant circuit 10, a first compressor 12, a first flow switching valve 13, a heat-source-side heat exchanger 14, a first expansion mechanism 15, and the first water heat exchanger 11 are sequentially connected by refrigerant pipes. It should be noted that the first refrigerant circuit 10 may include another component or other components in addition to the above components, and one or some of the above components of the first refrigerant circuit 10 may be omitted.

The first compressor 12 is, for example, an inverter compressor. In the case where the first compressor 12 is an inverter compressor, its operating frequency may be arbitrarily changed by, for example, an inverter circuit to change its capacity for discharging the refrigerant per time unit. In this case, the operation of the inverter circuit is controlled by the controller 6. The refrigerant discharged from the first compressor 12 flows into the heat-source-side heat exchanger 14 and/or the first water heat exchanger 11 through the first flow switching valve 13.

The first flow switching valve 13 is, for example, a four-way valve, and has a function of switching the flow passage for the refrigerant between plural flow passages. In a cooling operation, the first flow switching valve 13 switches the flow passage in such a manner as to connect a refrigerant discharge side of the first compressor 12 and the heat-source-side heat exchanger 14 and connect a refrigerant suction side of the first compressor 12 and the first water heat exchanger 11. In a heating operation, the first flow switching valve 13 switches the flow passage in such a manner as to connect the refrigerant discharge side of the first compressor 12 and the first water heat exchanger 11 and connect the refrigerant suction side of the first compressor 12 and the heat-source-side heat exchanger 14. It should be noted that the first flow switching valve 13 may be configured as a combination of two-way valves or a combination of three-way valves.

The heat-source-side heat exchanger 14 operates as a condenser in the cooling operation. The heat-source-side heat exchanger 14 operates as an evaporator in the heating operation. The heat-source-side heat exchanger 14 sucks outdoor air sent by a heat-source-side fan 16, and lets out air that exchanges heat with refrigerant flowing therein to the outside of the heat-source-side fan 16.

The first expansion mechanism 15 reduces the pressure of the refrigerant that flows in the first refrigerant circuit 10 to expand the refrigerant, and is, for example, an electronic expansion valve whose opening degree is variably controlled.

The first water heat exchanger 11 causes heat exchange to be performed between the heat medium and the refrigerant. The first water heat exchanger 11 serves as a flow passage for the first refrigerant circuit 10 and that for the first heat-medium circuit 4. To be more specific, the first water heat exchanger 11 is a component included in the first refrigerant circuit 10 and included in the first heat-medium circuit 4. In the cooling operation, the first water heat exchanger 11 operates as an evaporator, and causes heat exchange to be performed between the refrigerant that flows out from the first expansion mechanism 15 and the heat medium to evaporate and vaporize the refrigerant, and cool the heat medium. In the heating operation, the first water heat exchanger 11 operates as a condenser, and causes heat exchange to be performed between the refrigerant that flows therein from the first compressor 12 and the heat medium to condense and liquefy the refrigerant or change it into two-phase gas-liquid refrigerant, and heat the heat medium.

The relay unit 2 includes the second refrigerant circuit 20 in which the refrigerant is circulated, the second water heat exchanger 21 that exchanges heat with the second refrigerant circuit 20, the third water heat exchanger 22 that exchanges heat with the second refrigerant circuit 20, the first flow switching devices 4a and 5a that switch the flow passages for heat mediums that flow into the load units 3A and 3B to flow passages that connect with the first heat-medium circuit 4 or the second heat-medium circuit 5. In the second refrigerant circuit 20, a second compressor 23, a second flow switching valve 24, the second water heat exchanger 21, a second expansion mechanism 25, and the third water heat exchanger 22 are sequentially connected by refrigerant pipes. It should be noted that the second refrigerant circuit 20 may include another component or other components in addition to the above components, and one or some of the components of the second refrigerant circuit 20 may be omitted.

The second compressor 23 is, for example, an inverter compressor, and basically has the same configuration as the first compressor 12. Refrigerant discharged from the second compressor 23 flows into the second water heat exchanger 21 or the third water heat exchanger 22 via the second flow switching valve 24.

The second flow switching valve 24 is, for example, a four-way valve, and basically has the same configuration as the first flow switching valve 13. In the cooling operation, the second flow switching valve 24 switches the flow passage to a flow passage that connects a refrigerant discharge side of the second compressor 23 and the second water heat exchanger 21 and connects a refrigerant suction side of the second compressor 23 and the third water heat exchanger 22. In the heating operation the second flow switching valve 24 switches the flow passage to a flow passage that connects the refrigerant discharge side of the second compressor 23 and the third water heat exchanger 22 and connects the refrigerant suction side of the second compressor 23 and the second water heat exchanger 21. It should be noted that the second flow switching valve 24 may be a combination of two-wave vales or three-way valves.

The second expansion mechanism 25 reduces the pressure of refrigerant that is circulated in the second refrigerant circuit 20 to expand the refrigerant, and is, for example, an electronic expansion valve whose opening degree is variably controlled.

The second water heat exchanger 21 causes heat exchange to be performed between the heat medium and the refrigerant. The second water heat exchanger 21 is included in a flow passage in the second refrigerant circuit 20 and a flow passage in the first heat-medium circuit 4. That is, the second water heat exchanger 21 is a component included in the second refrigerant circuit 20 and also included in the first heat-medium circuit 4. It should be noted that in the second water heat exchanger 21 as illustrated in FIG. 1, in particular, in the case where the second water heat exchanger 21 operates as a condenser, it is preferable that piping be installed so that refrigerant circulating in the second refrigerant circuit 20 and a heat medium circulating in the first heat-medium circuit 4 flow as countercurrent to increase a heat exchange rate at the second water heat exchanger 21.

When operating as a condenser, the second water heat exchanger 21 causes heat exchange to be performed between the refrigerant that flows therein from the second compressor 23 and a heat medium that circulates through the first heat-medium pipe 40, thereby condensing and liquefying the refrigerant or changing the refrigerant into two-phase gas-liquid refrigerant, and also heating the heat medium. When operating as an evaporator, the second water heat exchanger 21 causes heat exchange to be performed between the refrigerant that flows out from the second expansion mechanism 25 and the heat medium that circulates through the first heat-medium pipe 40, thereby evaporating and vaporizing the refrigerant, and also cooling the heat medium.

The third water heat exchanger 22 causes heat exchange to be performed between the heat medium and the refrigerant. The third water heat exchanger 22 is included in a flow passage in the second refrigerant circuit 20 and a flow passage in the second heat-medium circuit 5. That is, the third water heat exchanger 22 is a component included in the second refrigerant circuit 20 and also included in the second heat-medium circuit 5. It should be noted that in the third water heat exchanger 22 as illustrated in FIG. 1, in particular, in the case where the third water heat exchanger 22 operates as a condenser, it is preferable that piping be installed so that refrigerant circulating in the second refrigerant circuit 20 and a heat medium circulating in the second heat-medium circuit 5 flow as countercurrent to increase a heat exchange rate at the third water heat exchanger 22.

When operating as an evaporator, the third water heat exchanger 22 causes heat exchange to be performed between the refrigerant that flows out from the second expansion mechanism 25 and the heat medium that circulates through the second heat-medium pipe 50, thereby evaporating and vaporizing the refrigerant, and also cooling the heat medium. When operating as a condenser, the third water heat exchanger 22 causes heat exchange to be performed between the refrigerant that flows thereinto from the second compressor 23 and the heat medium that circulates through the second heat-medium pipe 50, thereby condensing and liquefying the refrigerant or changing the refrigerant into two-phase gas-liquid refrigerant, and also heating the heat medium.

On a refrigerant inflow side and a refrigerant outflow side of each of the load-side heat exchangers 30, respective first flow switching devices 4a are provided in the first heat-medium circuit 4. Also, on the refrigerant inflow side and the refrigerant outflow side of the load-side heat exchanger 30, respective first flow switching devices 5a are provided in the second heat-medium circuit 5. The first flow switching devices 4a and 5a are, for example, two-way valves, and the opening and closing operations thereof are controlled by the controller 6. It should be noted that the first flow switching devices 4a and 5a may be, for example, two-way valves whose opening degrees (opening areas) can be controlled. When the opening and closing of the first flow switching devices 4a and 5a are controlled, the heat medium that flows into and out from the load-side heat exchanger 30 is controlled.

In the first heat-medium circuit 4, a first pump 41 is provided to circulate the heat medium. The first pump 41 is one of components that are included in the first heat-medium circuit 4. For example, the first pump 41 is provided in the heat source unit 1. In the first heat-medium circuit 4, the first pump 41 draws water, and gives a pressure to the water to send and circulate the water. The capacity of the first pump 41 is changed by a pump inverter drive device (not illustrated). The pump inverter drive device arbitrarily changes the drive frequency of the first pump 41 in response to an instruction given from the controller 6, thereby changing the capacity of the first pump 41.

FIG. 3 is a refrigerant circuit diagram illustrating a configuration of the heat pump apparatus 100 according to Embodiment 1, in which the first pump 41 is provided in the relay unit 2. FIG. 4 is a refrigerant circuit diagram illustrating a configuration of the heat pump apparatus 100 according to Embodiment 1, in which in the heat source unit 1 and the relay unit 2, respective first pumps 41 are provided. The first pump 41 may be provided in the relay unit 2 as illustrated in FIG. 3, and the first pumps 41 may be provided in the heat source unit 1 and the relay unit 2, respectively, as illustrated in FIG. 4. In the heat pump apparatus 100 as illustrated in FIG. 4, two first pumps 41 are connected in series in consideration of a pressure loss of the heat medium that flows between the heat source unit 1 and the relay unit 2 and a pressure loss of the heat medium that flows between the relay unit 2 and the load units 3A and 3B.

Furthermore, in the second heat-medium circuit 5, a second pump 51 is provided to circulate the heat medium. The second pump 51 is one of components included in the second heat-medium circuit 5. In the second heat-medium circuit 5, the second pump 51 draws water and gives a pressure to the water to send and circulate the water. The capacity of the second pump 51 is changed by the pump inverter drive device (not illustrated). The pump inverter drive device arbitrarily changes the drive frequency of the second pump 51 in response to an instruction given from the controller 6, thereby changing the capacity of the second pump 51.

The second pump 51 is smaller than the first pump 41 in flow rate or lifting range. In the second heat-medium circuit 5, the relay unit 2 is connected to the load units 3A and 3B, and the pressure loss is not large and heat-medium pipes are short, as compared with those of the first heat-medium circuit 4. By making the second pump 51 smaller than the first pump 41, it is possible to reduce the cost and the burden of an installation work load on a setting work. The second pump 51 may be the same as the first pump 41 in flow rate or lifting range.

The load units 3A and 3B include respective load-side heat exchangers 30 and respective load-side fans 31. The load units 3A and 3B each cause indoor air to pass through an associated one of the load-side heat exchangers 30 and generate an air flow that the indoor air to an associated indoor space. Each of the load-side heat exchanger 30 is, for example, a finned heat exchanger that causes heat exchange to be performed between indoor air in an associated indoor space that is supplied from the load-side fan 31 and the heat medium. In the cooling operation, a heat medium that is cooler than air passes through heat transfer tubes in the load-side heat exchanger 30, to thereby cool the indoor space. In the heating operation, a heat medium that is warmer than air passes through the heat transfer tubes in the load-side heat exchanger 30, to thereby heat the indoor space. It should be noted that although it is not illustrated, the load units 3A and 3B may include respective flow-rate adjusting devices configured to adjust the flow rates of the heat mediums that flow into the load-side heat exchangers 30.

The controller 6 controls the operation of the entire heat pump apparatus 100. Specifically, the controller 6 controls the drive frequency of the compressor, the rotational speeds of the fans, switching operations of the flow switching devices, the opening degrees of the expansion mechanisms, the drive frequencies of the pumps, etc. The controller 6 is a computer that includes a memory configured to store a program and data necessary for the control, and a CPU that runs the program, or dedicated hardware such as ASIC or FPGA, or a combination of the computer and the dedicated hardware.

Next, it will be described how the heat pump apparatus 100 operates in each of various operations. The operations of the heat pump apparatus 100 are the following four operations: the cooling operation; the heating operation; a cooling main operation, and a heating main operation.

In the cooling operation, the load units 3A and 3B are allowed to perform the cooling operation only, and each of the load units 3A and 3B is in the cooling operation or in the stopped state. In the heating operation, the load units 3A and 3B are allowed to perform the heating operation only, and each of the load units 3A and 3B is in the heating operation or in the stopped state. In the cooling main operation, each of the load units 3A and 3B is allowed to selectively perform cooling and heating and in a simultaneous cooling and heating operation in which one of the load units 3A and 3B performs cooling and the other of the load units 3A and 3B performs heating, a cooling load is greater than a heating load. In the heating main operation, each of the load units 3A and 3B is allowed to selectively cooling and heating and in the simultaneous cooling and heating operation in which one of the load units 3A and 3B performs cooling and the other of the load units 3A and 3B performs heating, the heating load is greater than the cooling load.

Cooling Operation

First of all, the cooling operation of the heat pump apparatus 100 will be described with reference to FIG. 5. FIG. 5 is a refrigerant circuit diagram of the heat pump apparatus 100 according to Embodiment 1, which indicates flows of the refrigerant and the heat medium in the case where the load units 3A and 3B perform cooling. It should be noted that devices denoted by reference sign “4a” are colored white, and this means that the devices 4a are in the open state; and devices denoted by reference sign “5a” are colored black, and this means that the devices 5a are in the closed state. In the heat pump apparatus 100 according to Embodiment 1, in the case where the load units 3A and 3B perform cooling, the first flow switching devices 4a are opened, the first flow switching devices 5a are closed, the second refrigerant circuit 20 is stopped, and only the first refrigerant circuit 10 and the first heat-medium circuit 4 are operated.

In the first refrigerant circuit 10, the high-temperature and high-pressure gas refrigerant discharged from the first compressor 12 passes through the first flow switching valve 13, and flows into the heat-source-side heat exchanger 14 to exchange heat with air and be condensed and liquefied thereby. The condensed and liquefied refrigerant is then decompressed at the first expansion mechanism 15 to change into low-pressure two-phase gas-liquid refrigerant, and the low-pressure two-phase gas-liquid refrigerant flows into the first water heat exchanger 11, exchanges heat with the heat medium that flows in the first heat-medium circuit 4, and as a result, is evaporated and gasified. The gasified refrigerant passes through the first flow switching valve 13 and is then sucked in the first compressor 12 through an accumulator.

On the other hand, the heat medium that flows in the first heat-medium circuit 4 is cooled by the refrigerant that flows through the first water heat exchanger 11 to change into cooled water, and the cooled water then flows into the load-side heat exchanger 30 through the relay unit 2, exchanges heat with indoor air in the indoor space, and is heated thereby. The heated heat medium passes through the relay unit 2 and then re-flows into the first water heat exchanger 11.

Heating Operation

Next, the heating operation of the heat pump apparatus 100 will be described with reference o FIG. 6. FIG. 6 is a refrigerant circuit diagram of the heat pump apparatus 100 according to Embodiment 1, which indicates flows of the refrigerant and a heat medium in the case where the load units 3A and 3B perform heating. It should be noted that the devices denoted by reference sign “4a” are colored white, and this means that the devices 4a are in the open state; and the devices denoted by reference sign “5a” are colored black, and this means that the devices 5a are in the closed state. In the heat pump apparatus 100 according to Embodiment 1, in the case where the load units 3A and 3B perform heating, the first flow switching devices 4a are opened, the first flow switching devices 5a are closed, the second refrigerant circuit 20 is stopped, and only the first refrigerant circuit 10 and the first heat-medium circuit 4 are operated.

In the first refrigerant circuit 10, the high-temperature and high-pressure gas refrigerant discharged from the first compressor 12 passes through the first flow switching valve 13 and flows into the first water heat exchanger 11. The refrigerant that has flowed into the first water heat exchanger 11 exchanges heat with the heat medium that flows in the first heat-medium circuit 4 and is condensed and liquefied. The condensed and liquefied refrigerant is decompressed at the first expansion mechanism 15 to change into low-pressure two-phase gas-liquid refrigerant, and the low-pressure two-phase gas-liquid refrigerant flows into the heat-source-side heat exchanger 14. The two-phase gas-liquid refrigerant that has flowed into the heat-source-side heat exchanger 14 exchanges heat with air and is evaporated and gasified thereby, and the evaporated and gasified refrigerant passes through the first flow switching valve 13 and is sucked into the first compressor 12 through the accumulator.

On the other hand, the heat medium that flows in the first heat-medium circuit 4 is heated by the refrigerant that flows through the first water heat exchanger 11 to change into heated water, and the heated water flows into the load-side heat exchanger 30 through the relay unit 2, exchanges heat with indoor air in the indoor space, and is cooled thereby. The cooled heat medium re-flows into the first water heat exchanger 11 through the relay unit 2.

Cooling Main Operation

The following description is made with reference to FIG. 7 and with respect to the cooling main operation in which the load unit 3A performs cooling, the load unit 3B performs heating, and the cooling load is great. FIG. 7 is a refrigerant circuit diagram of the heat pump apparatus 100 according to Embodiment 1, which indicates flows of the refrigerant and the heat medium in the cooling main operation.

In the heat pump apparatus 100, in the case where the load unit 3A performs cooling and the load unit 3B performs heating, the first refrigerant circuit 10, the first heat-medium circuit 4, the second refrigerant circuit 20, and the second heat-medium circuit 5 are operated. In order that the load-side heat exchanger 30 of the load unit 3A that performs cooling and the first heat-medium circuit 4 be connected to each other, the first flow switching devices 4a are opened, and the first flow switching devices 5a are closed. Furthermore, in order that the load-side heat exchanger 30 of the load unit 3B that performs heating and the second heat-medium circuit 5 be connected to each other, the first flow switching devices 4a are closed, and the first flow switching devices 5a is opened.

In the first refrigerant circuit 10, the high-temperature and high-pressure gas refrigerant discharged from the first compressor 12 passes through the first flow switching valve 13, flows into the heat-source-side heat exchanger 14, exchanges heat with air, and is condensed and liquefied thereby. The condensed and liquefied refrigerant is decompressed at the first expansion mechanism 15 to change into low-pressure two-phase gas-liquid refrigerant, and the low-pressure two-phase gas-liquid refrigerant flows into the second water heat exchanger 21, exchanges heat with the heat medium that flows in the first heat-medium circuit 4, and is evaporated and gasified thereby. The gasified refrigerant passes through the first flow switching valve 13 and is sucked into the first compressor 12 through the accumulator.

On the other hand, the heat medium that flows in the first heat-medium circuit 4 is cooled by the refrigerant that flows in the first water heat exchanger 11 to change into cooled water. Then, the cooled water flows into the load-side heat exchanger 30 of the load unit 3A through the relay unit 2, exchanges heat with indoor air in the indoor space, and is heated thereby. The heated heat medium flows into the second water heat exchanger 21, exchanges heat with the refrigerant that circulates in the second refrigerant circuit 20, and is cooled thereby. The cooled heat medium re-flows into the first water heat exchanger 11.

In the second refrigerant circuit 20, high-temperature and high-pressure gas refrigerant discharged from the second compressor 23 passes through the second flow switching valve 24, flows into the third water heat exchanger 22, exchanges heat with the heat medium that flows in the second heat-medium circuit 5, and as a result, is condensed and liquefied. The condensed and liquefied refrigerant is decompressed at the second expansion mechanism 25 to change into low-pressure two-phase gas-liquid refrigerant, and the low-pressure two-phase gas-liquid refrigerant flows into the second water heat exchanger 21, exchanges heat with the heat medium that flows in the first heat-medium circuit 4, and as a result, is evaporated and gasified. The gasified refrigerant passes through the second flow switching valve 24 and is sucked into the second compressor 23 via the accumulator.

On the other hand, the heat medium that flows in the second heat-medium circuit 5 is heated by the refrigerant that flows in the third water heat exchanger 22 to change into heated water, and the heated water flows into the load-side heat exchanger 30 of the load unit 3B, exchanges heat with indoor air in the indoor space, and as a result, is cooled. The cooled heat medium re-flows into the third water heat exchanger 22.

Heating Main operation

The following description is made with reference to FIG. 8 and with respect to a heating main operation in which the load unit 3A performs cooling, the load unit 3B performs heating, and the heating load is great. FIG. 8 is a refrigerant circuit diagram indicating flows of the refrigerant and the heat medium in the heating main operation in the heat pump apparatus according to Embodiment 1.

In the heat pump apparatus 100, in the case where the load unit 3A performs cooling and the load unit 3B performs heating, the first refrigerant circuit 10, the first heat-medium circuit 4, the second refrigerant circuit 20, and the second heat-medium circuit 5 are operated. Then, in order to connect the load-side heat exchanger 30 of the load unit 3A that performs cooling and the second heat-medium circuit 5, the first flow switching devices 4a are closed and the first flow switching devices 5a are opened. Furthermore, in order to connect the load-side heat exchanger 30 of the load unit 3B that performs heating and the first heat-medium circuit 4, the first flow switching devices 4a are opened and the first flow switching devices 5a are closed.

In the first refrigerant circuit 10, the high-temperature and high-pressure gas refrigerant discharged from the first compressor 12 passes through the first flow switching valve 13 and flows into the first water heat exchanger 11. The refrigerant that has flowed into the first water heat exchanger 11 exchanges heat with the heat medium that flows in the first heat-medium circuit 4, and as a result, is condensed and liquefied. The condensed and liquefied refrigerant is decompressed at the first expansion mechanism 15 to change into low-pressure two-phase gas-liquid refrigerant, and the low-pressure two-phase gas-liquid refrigerant flows into the heat-source-side heat exchanger 14. The two-phase gas-liquid refrigerant that has flowed into the heat-source-side heat exchanger 14 exchanges heat with air to be evaporated and gasified, and the gasified refrigerant passes through the first flow switching valve 13 and is sucked into the first compressor 12 via the accumulator.

On the other hand, the heat medium that flows in the first heat-medium circuit 4 is heated by the refrigerant that flows in the first water heat exchanger 11 to change into heated water, and the heated water flows into the load-side heat exchanger 30 of the load unit 3A through the relay unit 2, exchanges heat with indoor air in the indoor space, and is cooled thereby. The cooled refrigerant flows into the second water heat exchanger 21, exchanges heat with the refrigerant that circulates in the second refrigerant circuit 20, and as a result, is heated, and the heated refrigerant re-flow into the first water heat exchanger 11.

In the second refrigerant circuit 20, the high-temperature and high-pressure gas refrigerant discharged from the second compressor 23 passes through the second flow switching valve 24, flows into the second water heat exchanger 21, exchanges heat with the heat medium that flows in the first heat-medium circuit 4, and as a result, is condensed and liquefied. The condensed and liquefied refrigerant is decompressed at the second expansion mechanism 25 to change into low-pressure two-phase gas-liquid refrigerant, and the low-pressure two-phase gas-liquid refrigerant flows into the third water heat exchanger 22, exchanges heat with the heat medium that flows in the second heat-medium circuit 5, and as a result, is evaporated and gasified. The gasified refrigerant passes through the second flow switching valve 24 and is sucked into the second compressor 23 through the accumulator.

On the other hand, the heat medium that flows in the second heat-medium circuit 5 is cooled by the refrigerant that flows in the third water heat exchanger 22 to change into cooled water. The cooled water then flows into the load-side heat exchanger 30 of the load unit 3B, exchanges heat with indoor air in the indoor space, and as a result, is heated. The heated heat medium re-flows into the third water heat exchanger 22.

Simultaneous Heating and Heated-water Supply Operation

FIG. 9 is a refrigerant circuit diagram illustrating Modification 1 of the heat pump apparatus 100 according to Embodiment 1. The heat pump apparatus 100 as illustrated as Modification 1 in FIG. 9 includes a hot-water storage tank that serves as a load unit 3C and supplies hot water. In FIG. 9, one of load units is the load unit 3B serving as an indoor unit and the other is the load unit 3C serving as the hot-water storage tank. The following description regarding FIG. 9 is made by referring to by way of example the case where the load unit 3B performs heating; however, the load unit 3B may perform cooling. Furthermore, it is assumed by way of example that referring to FIG. 9, the load of the heating is greater than that of the heated-water supply.

The heat medium that circulates in the second heat-medium circuit 5 is water that is supplied to the heated-water supply tank serving as the load unit 3C. The heated-water supply tank stores water that is supplied through a water supply pipe and hot water that is heated at the third water heat exchanger 22.

In the heat pump apparatus 100, in the case where the load unit 3B performs heating and the load unit 3C performs heated-water supply, the first refrigerant circuit 10, the first heat-medium circuit 4, the second refrigerant circuit 20, and the second heat-medium circuit 5 are operated. Furthermore, in order to connect the load-side heat exchanger 30 of the load unit 3B that performs heating and the first heat-medium circuit 4, the first flow switching devices 4a are opened and the first flow switching devices 5a are closed. In addition, in order to connect the load-side heat exchanger 30 of the load unit 3C that performs heated-water supply and the second heat-medium circuit 5, the first flow switching devices 4a are closed and the first flow switching devices 5a are opened.

In the first refrigerant circuit 10, the high-temperature and high-pressure gas refrigerant discharged from the first compressor 12 passes through the first flow switching valve 13 and flows into the first water heat exchanger 11. The refrigerant that has flowed into the first water heat exchanger 11 exchanges heat with the heat medium that flows in the first heat-medium circuit 4, and as a result, is condensed and liquefied. The condensed and liquefied refrigerant is decompressed at the first expansion mechanism 15 to change into low-pressure two-phase gas-liquid refrigerant, and the low-pressure two-phase gas-liquid refrigerant flows into the heat-source-side heat exchanger 14. The two-phase gas-liquid refrigerant that has flowed into the heat-source-side heat exchanger 14 exchanges heat with air and is evaporated and gasified thereby. The gasified refrigerant passes through the first flow switching valve 13 and is sucked into the first compressor 12 through the accumulator.

On the other hand, the heat medium that flows in the first heat-medium circuit 4 is heated by the refrigerant that flows in the first water heat exchanger 11 to change into heated water. The heated water flows into the load-side heat exchanger 30 of the load unit 3B via the relay unit 2, exchanges heat with indoor air in the indoor space, and is cooled thereby. The cooled heat medium flows into the second water heat exchanger 21 exchanges heat with the refrigerant that circulates in the second refrigerant circuit 20, is cooled thereby, and re-flows into the first water heat exchanger 11.

In the second refrigerant circuit 20, the high-temperature and high-pressure gas refrigerant discharged from the second compressor 23 passes through the second flow switching valve 24, flows into the third water heat exchanger 22, exchanges heat with the heat medium that flows in the second heat-medium circuit 5, and is condensed and liquefied thereby. The condensed and liquefied refrigerant is decompressed at the second expansion mechanism 25 to change into low-pressure two-phase gas-liquid refrigerant. The low-pressure two-phase gas-liquid refrigerant flows into the second water heat exchanger 21 and exchanges heat with the heat medium that flows in the first heat-medium circuit 4, and is evaporated and gasified thereby. The gasified refrigerant passes through the second flow switching valve 24 and is sucked into the second compressor 23 through the accumulator.

On the other hand, the heat medium that flows into the second heat-medium circuit 5 is heated by the refrigerant that flows in the third water heat exchanger 22 to change into heated water, and the heated water is stored in the hot-water storage tank.

It should be noted that both the load unit 3B and 3C may be heated-water supply tanks that perform heated-water supply. In this case, the second flow switching valve 24 may be omitted from the second refrigerant circuit 20.

FIG. 10 is a configuration diagram schematically illustrating Modification 2 of the heat pump apparatus 100 according to Embodiment 1. The number of heat source units 1, that of relay units 2, that of load units 3A, and that of load units 3B are not limited to the numbers of heat source units 1, relay units 2, load units 3A, and load units 3B that are explained above. As illustrated in FIG. 10, two or more heat source units 1 may be installed. In the case where a plurality of heat source units 1 are installed, first heat-medium pipes thereof are connected to each other. Also, two or more relay units 2 may be installed. In the case where a plurality of relay units 2 are installed, first heat-medium pipes thereof are connected to each other. To each of the relay units 2, three or more load units 3A and 3B may be connected. In this case, all the load units 3A and 3B may be indoor units, or one or some of the load units 3A and 3B or all the load units 3A and 3B may be heated-water supply tanks that perform heated-water supply; and one or some of the load units 3A and 3B may be directly connected to the heat source unit 1 or units 1 without passing through the relay unit 2.

As described above, the heat pump apparatus 100 according to Embodiment 1 includes the heat source unit 1, the relay unit 2 connected to the heat source unit 1, and the load units 3A and 3B connected to the relay unit 2. The heat source unit 1 includes the first refrigerant circuit 10 in which the refrigerant circulates and the first water heat exchanger 11 that exchanges heat with the first refrigerant circuit 10. The relay unit 2 includes the second refrigerant circuit 20 in which the refrigerant circulates and the second water heat exchanger 21 that exchanges heat with the second refrigerant circuit 20. The first water heat exchanger 11, the second water heat exchanger 21, and the load units 3A and 3B are connected by the first heat-medium pipes 40, whereby the first heat-medium circuit 4 is formed in which the heat medium circulates.

Therefore, in the heat pump apparatus 100 according to Embodiment 1, when the load units 3A and 3B perform cooling and heating at the same time, the first refrigerant circuit 10 provided in the heat source unit 1 and the second refrigerant circuit 20 provided in the relay unit 2 can perform cooling or heating and heating or cooling, respectively. Therefore, in the heat pump apparatus 100, since the number of pipes that connect the heat source unit 1 and the relay unit 2 can be reduced to two, that is, a smaller number of pipes are installed, it is possible to reduce the burden of the piping work.

Embodiment 2

The heat pump apparatus 101 according to Embodiment 2 will be described with reference to FIGS. 11 and 12. FIG. 11 is a refrigerant circuit diagram of the heat pump apparatus 101 according to Embodiment 2. It should be noted that regarding the heat pump apparatus 101, components that are the same as the heat pump apparatus 100 that are described with respect to Embodiment 1 are denoted by the same reference signs, and their descriptions will be omitted as appropriate.

In the heat pump apparatus 100, in the case where the load units 3A and 3B perform cooling and heating at the same time, the second refrigerant circuit 20 and the second heat-medium circuit 5 are operated, and as a result, in the heat source unit 1the load for generating cooling or heating water is reduced. Therefore, in this case, not all the heat mediums that flow in the first heat-medium circuit 4 need to be made to flow into the first water heat exchanger 11.

In view of the above, in the heat pump apparatus 101 according to Embodiment 2, in the first heat-medium circuit 4, a bypass flow passage 7 and a flow control device 8 are provided. The bypass flow passage 7 connects the first heat-medium pipe 40 located between the first water heat exchanger 11 and the second water heat exchanger 21 and the first heat-medium pipe 40 located between the first water heat exchanger 11 and the load-side heat exchanger 30. The flow control device 8 regulates the flow rate of the heat medium that flows into the first water heat exchanger 11 and the flow rate of the heat medium that flows into an outlet side of the first water heat exchanger 11 via the bypass flow passage 7. The flow control device 8 includes a first flow control valve 8a that is provided between an inlet end of the bypass flow passage 7 and the first water heat exchanger 11 and a second flow control valve 8b that is provided at the bypass flow passage 7. In the heat pump apparatus 101, in the case where the load units 3A and 3B perform cooling and heating at the same time, it is possible to regulate the flow rate of the heat medium that flows in the first water heat exchanger 11 and that of the heat medium that flows in the bypass flow passage 7 by controlling the first flow control valve 8a and the second flow control valve 8b.

The first flow control valve 8a and the second flow control valve 8b are each, for example, a two-way valve whose opening degree (opening area) can be controlled.

The first flow control valve 8a controls the flow rate of a heat medium that flows into the first water heat exchanger 11 by regulation of the opening degree of the first flow control valve 8a. The second flow control valve 8b controls the flow rate of a heat medium that flows into the bypass flow passage 7 by regulation of the opening degree of the second flow control valve 8b. The first flow control valve 8a and the second flow control valve 8b are controlled by the controller 6.

FIG. 12 is a graph indicating a relationship indicating a relationship between a cooling ratio of the load units 3A and 3B and a ratio of a flow rate V1 of the heat medium that flows in the bypass flow passage 7 to the total flow rate V of the heat mediums that flow in the first heat-medium circuit 4 in the heat pump apparatus 101 according to Embodiment 2. The horizontal axis represents the cooling ratio of the load units 3A and 3B and the vertical axis represents the ratio of the flow rate V1 of the heat medium that flows in the bypass flow passage 7 to the total flow rate V of the heat mediums that flow in the first heat-medium circuit 4. On the horizontal axis, 100% indicates a state in which the load units 3A and 3B perform cooling only, and 0% indicates a state that the load units 3A and 3B perform heating only.

As indicated in FIG. 12, in the case where the load units 3A and 3B perform cooling only or heating only, that is, the cooling ratio on the load side is 100% or 0%, the first flow control valve 8a is completely opened and the second flow control valve 8b is completely closed, whereby the ratio of the flow rate V1 of the heat medium that flows in the bypass flow passage 7 to the total flow rate V of the heat mediums that flow in the first heat-medium circuit 4 is set to 0%.

By contrast, in the case where the load units 3A and 3B perform cooling and heating at the same time, the opening degrees of the first flow control valve 8a and the second flow control valve 8b are controlled according to the cooling ratio of the load units 3A and 3B, thereby adjusting the ratio of the flow rate V1 of the heat medium that flows in the bypass flow passage 7 to the total flow rate V of the heat mediums that flow in the first heat-medium circuit 4. As a result, it is possible to reduce a flow rate v2 of the heat medium that flows in the heat source unit 1, and thus improve the heat-exchange efficiency.

It should be noted that in the case where the cooling load and heating load of the load units 3A and 3B do not vary (at point A in FIG. 12), the first flow control valve 8a is completely closed and the second flow control valve 8b is completely opened, whereby the flow rate V1 of the heat medium that flows in the bypass flow passage 7 is set to 100%. As a result, it is possible to stop the operation of the heat source unit 1 and thus improve the energy-saving efficiency of the heat pump apparatus 100.

In the example illustrated in the figure, the bypass flow passage 7 is provided in the relay unit 2; however, the bypass flow passage may be provided in the heat source unit 1. Furthermore, in the heat pump apparatus 101 according to Embodiment 2, as illustrated in FIG. 9, a load unit may be formed as a hot-water storage tank that performs heated-water supply.

Embodiment 3

Next, a heat pump apparatus 102 according to Embodiment 3 will be described with reference to FIGS. 13 to 15. FIG. 13 is a refrigerant circuit diagram of the heat pump apparatus 102 according to Embodiment 3. It should be noted that regarding the heat pump apparatus 102, components that are the same as those of the heat pump apparatus 100 described regarding Embodiment 1 will be denoted by the same reference signs, and their descriptions will thus be omitted as appropriate.

In the heat pump apparatus 102 according to Embodiment 3, in the first water heat exchanger 11, piping is installed so that the refrigerant that circulates in the first refrigerant circuit 10 and the heat medium that circulates in the first heat-medium circuit 4 flow as countercurrent, to thereby improve the heat-exchange efficiency at the first water heat exchanger 11 and also improve the energy saving efficiency. The heat pump apparatus 102 according to Embodiment 3 is effective, especially, in the case of using a zeotropic refrigerant mixture whose boiling point and dew point are different, and it is possible to reduce the temperature difference between the refrigerant and water in each of a condensing process of the refrigerant (in which water is heated) and an evaporating process of the refrigerant (in which water is cooled), as a result of which the system efficiency is improved.

As illustrated in FIG. 13, the first heat-medium circuit 4 of the heat pump apparatus 102 includes a second flow switching device 9 that reverses the flow of the heat medium that flows into the first water heat exchanger 11. The second flow switching device 9 includes a first bypass pipe 90, a second bypass pipe 91, a first on-off valve 92, a second on-off valve 93, a third on-off valve 94, and a fourth on-off valve 95 The first bypass pipe 90 has a first inlet end 90a and a first outlet end 90b. The first inlet end 90a is connected to the first heat-medium pipe 40 located between the first water heat exchanger 11 and the second water heat exchanger 21, and the first outlet end 90b is connected to the first heat-medium pipe 40 located between the first water heat exchanger 11 and the load units 3A and 3B. The second bypass pipe 91 has a second inlet end 91a and a second outlet end 91b. The second inlet end 91a is connected to the first heat-medium pipe 40 located between the first water heat exchanger 11 and the first inlet end 90a of the first bypass pipe 90. The second outlet end 91b is connected to the first heat-medium pipe 40 located between the first outlet end 90b of the first bypass pipe 90 and the load units 3A and 3B.

The first on-off valve 92 is provided at the first heat-medium pipe 40 located between the first inlet end 90a of the first bypass pipe 90 and the second inlet end 91a of the second bypass pipe 91. The second on-off valve 93 is provided at the first bypass pipe 90. The third on-off valve 94 is provided at the second bypass pipe 91. The fourth on-off valve 95 is provided at the first heat-medium pipe 40 located between the first outlet end 90b of the first bypass pipe 90 and the second outlet end 91b of the second bypass pipe 91. The first on-off valve 92, the second on-off valve 93, the third on-off valve 94, and the fourth on-off valve 95 are each, for example, a two-way valve, and opening and closing of each of those valves is controlled by the controller 6.

FIG. 14 is a refrigerant circuit diagram of the heat pump apparatus 102 according to Embodiment 3 in the case where heated water is generated in the first heat-medium circuit 4. It should be noted that valves denoted by reference signs “92” and “95” are colored white and this means that the valves are in the open state; and valves denoted by reference signs “92” and “95” are colored black and this means that the valves are in the closed state. In the heat pump apparatus 102, as illustrated in FIG. 14, in the case where heated water is generated by the first heat-medium circuit 4, the first on-off valve 92 and the fourth on-off valve 95 are opened, and the second on-off valve 93 and the third on-off valve 94 are closed. In this case, the heat medium that flows in the first heat-medium circuit 4 flows from the second water heat exchanger 21 to the first water heat exchanger 11 and is heated by the refrigerant flowing in the first water heat exchanger 11 to change into heated water, and the heated water flows to the load-side heat exchanger 30, exchanges heat with indoor air in the indoor space, and is cooled thereby. In the first refrigerant circuit 10, the high-temperature and high-pressure gas refrigerant discharged from the first compressor 12 passes through the first flow switching valve 13 and flows to the first water heat exchanger 11. That is, in the first water heat exchanger 11, the refrigerant that circulates in the first refrigerant circuit 10 and the heat medium that circulates in the first heat-medium circuit 4 flow as countercurrent.

FIG. 15 is a refrigerant circuit diagram of the heat pump apparatus 102 according to Embodiment 3 in the case where cooled water is generated by the first heat-medium circuit 4. It should be noted that valves denoted by reference signs “93” and “94” are colored white and this means that the valves are in the open state; and the valves denoted by reference signs “92” and “95” are colored black and this means that the valves are in the closed state. In the heat pump apparatus 102, as illustrated in FIG. 15, in the case where cooled water is generated by the first heat-medium circuit 4, the first on-off valve 92 and the fourth on-off valve 95 are closed and the second on-off valve 93 and the third on-off valve 94 are opened. In this case, the heat medium that flows in the first heat-medium circuit 4 flows from the second water heat exchanger 21 to the first bypass pipe 90 and then to the first water heat exchanger 11. The heat medium that has flowed to the first water heat exchanger 11 is cooled by the refrigerant that flows in the first water heat exchanger 11 to change into cooled water. The cooled water flows to the second bypass pipe 91 and then to the load-side heat exchanger 30, exchanges heat with indoor air in the indoor space, and is heated thereby. In the first refrigerant circuit 10, the high-temperature and high-pressure gas refrigerant discharged from the first compressor 12 passes through the first flow switching valve 13, flows to the heat-source-side heat exchanger 14, exchanges heat with air, and is condensed and liquefied thereby. The condensed and liquefied refrigerant is decompressed at the first expansion mechanism 15 to change into low-pressure two-phase gas-liquid refrigerant, and the low-pressure two-phase gas-liquid refrigerant flows to the first water heat exchanger 11. That is, in the first water heat exchanger 11, the refrigerant that circulates in the first refrigerant circuit 10 and the heat medium that circulates in the first heat-medium circuit 4 flow as countercurrent.

As described above, in the heat pump apparatus 102 according to Embodiment 3, in the first water heat exchanger 11, it is possible to improve the heat-exchange efficiency and the energy-saving efficiency, because the refrigerant that circulates in the first refrigerant circuit 10 and the heat medium that circulates in the first heat-medium circuit 4 flow as countercurrent.

The above descriptions refer to the heat pump apparatuses (100 to 102) according the embodiments; however, the configurations of the heat pump apparatuses (100 to 102) are not limited to the configurations described above regarding the embodiments. The above configurations of the heat pump apparatuses (100 to 102) are described as examples, and the heat pump apparatuses (100 to 102) may include other components or some of the components of the heat pump apparatuses (100 to 102) may be omitted. That is, design modifications and applications of the heat pump apparatuses (100 to 102) can be made within a range in which a person with ordinary skill in the art would ordinarily make them without departing from the technical concept of the heat pump apparatuses (100 to 102).

REFERENCE SIGNS LIST

• • 1: heat source unit, 2: relay unit, 3A, 3B: load unit, 4: first heat-medium circuit, 4a: first flow switching device, 5: second heat-medium circuit, 5a: first flow switching device, 6: controller, 7: bypass flow passage, 8: flow control device, 8a: first flow control valve, 8b: second flow control valve, 9: second flow switching device, 10: first refrigerant circuit, 11: first water heat exchanger, 12: first compressor, 13: first flow switching valve, 14: heat-source-side heat exchanger, 15: first expansion mechanism, 16: heat-source-side fan, 20: second refrigerant circuit, 21: second water heat exchanger, 22: third water heat exchanger, 23: second compressor, 24: second flow switching valve, 25: second expansion mechanism, 30: load-side heat exchanger, 31: load-side fan, 40: first heat-medium pipe, 41: first pump, 50: second heat-medium pipe, 51: second pump, 90: first bypass pipe, 90a: first inlet end, 90b: first outlet end, 91: second bypass pipe, 91a: second inlet end, 91b: second outlet end, 92: first on-off valve, 93: second on-off valve, 94: third on-off valve, 95: fourth on-off valve, 10, 101, 102: heat pump apparatus, 200: building